The invention relates to an electrooptical transmitting and/or receiving module, and a method for producing the module. The invention is in the field of the production of electrooptical assemblies or modules that usually have a plug receptacle for connecting and optically coupling suitable coupling partners, for example optical conductors. Also conceivable as coupling partners are other optical or electrooptical elements: e.g. for electrically isolating from a further electrooptical module. For converting electrical signals into optical ones or for converting optical signals into electrical ones, such modules have electrooptical transducers that have a light-emitting (transmitter) or light-sensitive (receiver) region that is also designated as optically active zone within the scope of the present invention. In addition to the electrooptical transformation of the signals, a high coupling efficiency in the case of feeding optical signals into or out of waveguides also requires precise coupling of the signal-exporting and/or signal feeding optical conductors (coupling partners). Light emitting diodes (LEDs) or horizontally radiating laser diodes, for example, are used as transmitters in optical communications engineering. Depending on the construction, these frequently have a large numerical aperture that requires the use of lenses for optical coupling with high efficiency.
Such a transmitting/receiving module is disclosed, for example, in commonly-owned, published, non-prosecuted German Patent Application No. DE 197 11 138 A1, which corresponds to U.S. Pat. No. 6,312,624. In the case of the production method described therein for an electrooptical module, a support, in general a lead frame, is positioned exactly by a positioning element dedicated to the support in a component insertion device in which a transducer is disposed and fixed on the support in the precise relative position in relation to the positioning element. The support is subsequently positioned exactly by the positioning element in a potting mould and surrounded by a formable material with the formation of a shaped body, the shaped body having a functional surface serving the purpose of optical coupling, for example a lens or a stop surface. The transducer can be either a transmitter, such as a semiconductor laser, or a receiver, such as a semiconductor photodiode. In the case of this electrooptical module, it is provided that the radiation beam emitted by a transmitter, or a radiation beam detected by a receiver covers a direct and straight light path between a light entry or light exit surface of the module and the transmitter/receiver. However, this restricts the possibilities of structural implementation of the electrooptical module, since it must always be ensured during production that the light entry or light exit surface of the transmitting or receiving surface of the transducer lie directly opposite. The selection of a specific transmitter, for example a vertically emitting vertical resonator semiconductor laser diode (VCSEL), thereby determines the shape of the module and of the shaped body. Conversely, the shape of the module, in particular the relative position of the lead frame in relation to the light exit side mostly prescribes the type of the transmitter to be used.
It is accordingly an object of the invention to provide an electrooptical transmitting/receiving module and a method for producing the module that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that ensure a more flexible construction of the module that is independent of the type of transmitter or receiver, is ensured. In particular, an object of the present invention is to specify an electrooptical module and a method for producing the module in which the light of the radiation beam is deflected inside the shaped body.
Consequently, the invention describes an electrooptical transmitting and/or receiving module having a shaped body, a first lead frame, and a reflector element. The shaped body is made from a transparent, formable material. The first lead frame is surrounded by the shaped body at least on a section on which an optoelectronic transducer is mounted. The reflector element is surrounded at least partially by the shaped body and has a reflecting surface that faces the transducer in such a way that it deflects by a predetermined angle a radiation beam in a light path between the transducer and a light entry or light exit side of the module.
In an electrooptical module according to the invention, the described reflector element can reflect a radiation beam emitted by a receiver in the direction of a prescribed light exit surface. Likewise, the described reflector element can deflect in the direction of a receiver a radiation beam launched into the module through a light entrance surface. The reflector element is dispose in a fixed relative position with reference to the transducer, because it is surrounded, together with the transducer or the section on which the transducer is mounted by the transparent, formable material.
Likewise, the invention describes a method for producing an electrooptical module having a shaped body made from a transparent formable material. In the method, an optoelectronic transducer is mounted on a section of a first lead frame. A reflector element having a reflecting surface is positioned in such a way relative to the first lead frame and the optoelectronic transducer that the reflecting surface deflects by a predetermined angle a radiation beam in the light path between the transducer and a provided light entry or light exit side of the module. The shaped body is formed by the virtue of the fact that the first lead frame and the reflector element are potted or encapsulated with the aid of the transparent formable material.
During production of the transmitting and/or receiving module according to the invention, an initially spatially coherent lead frame is formed in a way known per se and provided with optoelectronic transducers on sections provided for the purpose. Only subsequently and mostly between different phases of a casting or injection operation are individual connecting webs between different connecting sections of the lead frame severed. It is thus also possible in the case of the module according to the invention for a plurality of transducers, that is to say in principle an arbitrary number of transmitters and/or receivers, to be mounted on coherent sections of the lead frame or sections of the lead frame separated from one another in the final stage.
As a rule, the reflector element is directed with its reflecting surface with reference to the optoelectronic transducer in such a way that an emitting or a receiving radiation beam describes a light path in which a beam deflection by an angle of 90xc2x0 is included. Because the shaped body mostly has a cuboid shape, the possibility is thereby created of deflecting an emitted radiation beam at a right angle onto a provided light exit surface of the shaped body. A degree of freedom is thereby gained in selecting between two different semiconductor lasers, specifically, an edge-emitting semiconductor laser and a vertically emitting semiconductor laser, such as a vertical resonator semiconductor laser (VCSEL).
There are various possibilities for producing and positioning the reflector element relative to the lead frame holding the transducer.
In a first embodiment of the present invention, the lead frame holding the transducer and the reflector element are formed from an originally unipartide lead frame. During the potting operation or the encapsulation of the lead frame with the transparent, formable material, it is then possible for the lead frame holding the transducer and the reflector element to be separated from one another. They can also, however, be connected to one another in the final stage of the electrooptical transmitting/receiving module. If, for example, the transmitter is an edge-emitting semiconductor laser that is mounted on an end section of a lead frame, a reflecting surface connected to the end section can be disposed at a spacing from the end section in the direction in which the semiconductor laser emits light. The reflecting surface can assume a 45xc2x0 angle to the incidence direction of the radiation beam emitted by the semiconductor laser, such that the reflecting surface deflects the radiation beam by a 90xc2x0 angle. The reflector element can be formed in the case of this embodiment by virtue of the fact that before or after a transmitter emitting in the direction of the plane of the lead frame, such as an edge-emitting semiconductor laser, is mounted on the lead frame a section of the lead frame lying upstream of the light exit surface of the transmitter is bent up until it assumes an angle of, in particular, 45xc2x0 with the plane of the lead frame.
However, it can also be provided in accordance with the second embodiment that the reflector element is separated straightaway from the lead frame provided with a transducer and is brought into position with its reflecting surface relative to the lead frame or the transducer before the potting or encapsulating operation. This relative positioning can be performed, for example, by a suitable positioning device.
For example, the reflector element can be developed from a second lead frame in the case of which, in order to produce the reflecting surface, a section is bent out of the plane of the second lead frame until it assumes an angle of, in particular, 45xc2x0 with the plane of the second lead frame.
When producing the electrooptical transmitting/receiving module, it is possible to use a mold. The mold determines the shape and size of the shaped body. After the potting or encapsulating operation, in which the transparent, formable material is introduced into the mold, the mold can be retained as module housing. A plug receptacle for coupling an optical conductor plug can be integrally formed on this housing on the light entry or light exit side. Such a module housing is also known as cavity as interface (CAI). However, it is likewise possible to provide that the mold is removed again after the formation of the shaped body. In this case, as well, it is possible for a plug receptacle, known as a so-called insertion socket, to be formed in the shaped body, in a functional surface thereof which is located on the light entry or light exit side, as is known per se in the prior art, for example DE 197 11 138 A1 as referenced above.
It can also be provided that a positive lens is formed in the transparent, formable material on the light entry or light exit side of the shaped body. For this purpose, the mold has on the provided light entry or light exit side of the module an opening in which there is located a shaped part that corresponds on its inner side to the outer contour of a lens to be formed, and that is removed after the formation of the shaped body.
It is possible to provide a plurality of optoelectronic transducers, for example a transmitter and a receiver, in a common transmitting/receiving module. These can be mounted on a common lead frame or on lead frame sections separated from one another. It can be provided in this case that a transmitter emits a radiation beam on a direct path, that is to say without beam deflection, in the direction of a light exit side, and that a received radiation beam entering the module is deflected by a reflecting surface in the direction of a receiver. Conversely, it can also be provided that a radiation beam emitted by a transmitter is deflected by a reflecting surface of a reflector element and then coupled out, while a received radiation beam is launched and directed straight onto a receiver without beam deflection. In the case of the use of a positive lens, the same positive lens can be used in each case for both radiation beams.
A preferred application of the electrooptical transmitting and/or receiving module according to the invention includes installing it in a compact transmitting and/or receiving unit, which is also designated as sidelooker, because a radiation beam can be launched or coupled out laterally, that is to say in a direction parallel to the plane of the circuit boards. It is possible here, in turn, to distinguish two embodiments from one another. In the first embodiment, the electrooptical transmitting and/or receiving module are constructed as a surface-mountable component (SMT, Surface Mounting Technology). In this case, the individual lead frame sections are guided laterally out of the shaped body and bent downwards around the shaped body in such a way that they form flat connecting sections that lie in a common mounting plane and with which they can be soldered onto a circuit board, for example using the reflow method. In this first embodiment, the lead frame plane is therefore parallel to the plane of the circuit board. In a second embodiment of the transmitting and/or receiving unit, the individual lead frame sections led out on one side of the module are plugged into the circuit board at right angles thereto and are connected to electric conductor tracks on the rear of the circuit board or an intermediate level of metallization of a multilayer circuit board. In the case of both embodiments, it becomes clear how the present invention provides more freedom of configuration by virtue of the fact that, depending on the selection of the embodiment, it is possible arbitrary to select the type of transmitter, and thus, for example, to select between an edge-emitting semiconductor laser and a vertically emitting semiconductor laser.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an electrooptical transmitting/receiving module, and a method for producing the module, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.